The Benefits Of High Mileage
[Written by Hal Higdon]
Will running very high mileage actually make you a better runner? It can – but the main reason why it can isn’t what you’d expect. It won’t necessarily improve your aerobic or anaerobic threshold, VO2 Max or general fitness, but it will improve your ability to use fat as an energy source and this is key for racing a marathon.
The late physiologist Al Claremont claimed that high mileage helps you better utilise glycogen, the starchlike substance stored in the liver and muscles that changes into a simple sugar as the body needs it. Carbohydrates in our diet are our main source of glycogen – one reason spaghetti is such a popular pre race meal for marathoners. Glycogen is the preferred fuel for running, but your levels can become depleted within 60 to 90 minutes. Thereafter, your source of fuel is fat, which is metabolised less efficiently.
Claremont believed high mileage running in essence teaches your body to burn more fat along with glycogen, stretching your reserves from 60 to 90 minutes to 2 hours or more. He explained “Top marathoners are probably so efficient in metabolising both fats and glycogen throughout the length of their races (because of the vast volume of their training) that they probably rarely deplete their stores. As a result, they don’t hit the wall.”
William J Fink of Ball State University in Muncie, Indiana suggests that volume training may result in a more efficient use of your muscle fibres. “When a runner doubles his training mileage, we often see no change in his maximum oxygen uptake, the ability to deliver oxygen to the muscles. This indicates something else – perhaps improved muscle fibres – causes the better performances.”
Jack H Wilmore, PhD at the University of Texas at El Paso suggests that there is a psychological effect to high mileage as well. “When you do 100+ miles (160+ km) a week, your legs are chronically fatigued. Then when you finally do taper before an important race, it makes you feel all the stronger. The same would hold for a 30 mile-a-week (48km a week) runner who through a gradual buildup achieved an ability to train comfortably at 60.”
Finally, Dr Wilmore says mileage helps your body adapt to the punishment that occurs during marathons. – in ways that scientists can’t even explain yet. “When I’m out of shape and I race at long distances, everything hurts.” he says. “It feels like my connective tissues are coming apart. But when I’m ready for a marathon and have put in the miles, everything moves smoothly.”
